Hi Angela
I believe you can rent the long tail to take you wherever you want. I don't know the cost though. Since you intend to rent it for your own family, you can probably negotiate the price. However, if you share the boat with others, the fee is usually fixed.
For kayak tours, the price includes a guide, lunch, water, life vests. You can choose to kayak w/o a guide, but that's probably not advisable, especially if you bring children along. Alternatively, you can just kayak along the beach, but that's kinda boring.
Zenn,
Not much to do at Ao NAng beach. It is nothing like Patong beach..so no jet skis, jet boats, parasailing etc. But it's kinda nice coz it's quieter and more laid back.
As for restaurants, I can't remember names. However, most of the food were good..we tried a few different restaurants and were not disappointed. Remember to try the pancake snacks sold at roadside stalls. The banana chocolate pancakes (like prata) are absolutely delicious!